Towed targets, either aerial or underwater, require tow cables which can withstand high tensile loads resulting from the drag of the target being pulled through an air or water medium. Cables as currently used are 1.times.19 strand compacted armored cables having eighteen strand wires surrounding a center core wire, compacted 1.times.7 strand cables comprising six strand wires surrounding a center core wire and strand wire double-compacted 3.times.7 cables comprising three strands surrounding a center core wire where each strand itself comprises six strand wires surrounding a center core strand wire. In order to reduce the diameter or cross-sectional bulk of such cables and thus drag forces imparted as the cables move through air or water, they are compacted by swaging tools. In the case of the 1.times.19 and 1.times.7 cables, they are subjected to one compacting operation whereas in the double-compacted 3.times.7 cable, each 1.times.7 strand is subjected to one compacting operation and the three 1.times.7 strands are then subjected to a further or second compacting operation.
While such cables provide sufficient tensile strength, have a high strength- to-diameter ratio, and are torsionally stable, they lack any transmission capabilities by which electrical power, electrical signals or signals may be transmitted between the towed target and the towing vehicle. With the more sophisticated targets being currently used, it is often desirable to connect the target to power sources to actuate infra-red transmitters on the target or to provide the target with hit indicators which may transmit hit signals to the towing vehicle.
Coaxial cables have been proposed to provide both tensile strength and transmitting qualities. Such cables comprise concentric layers of electrical conductors or strength elements separated by layers of insulation with the result that the cables have poor torsionial stability which limits their utility.
It has also been proposed to combine tensile strength elements along with electrical conductors having shielding or to use fiber optic and hollow conductive elements arranged within a protective matrix to provide a cable having both high tensile strength and transmitting characteristics. However transmitting elements, particularly hollow conduits or fiber optics, are not susceptible to compacting operations without risk of damage with the result that such cables have a low maximum strength-to-diameter ratio such that their drag characteristics are objectionable.
It is therefore an object of my invention to provide for a high tensile strength transmission cable which has a transmission element therein and which at the same time has high strength-to-diameter ratio to reduce drag as the cable is pulled through a fluid medium.
It is a further object of my invention to provide for a method by which a high tensile strength transmission cable may be made from a pre-compacted multi-strand cable and where the high strength transmission cable will have transmission elements therein which are not subjected to compaction forces.